Electric switch



Jan. 25, 1938. K. J. UNWIN 2,106,581

ELECTRIC swncn Filed Oct. 51 1956 2 Sheets-Sheet 1 Fig.1. -Fig.2.

2f 8 2 L 37 2f Ihvntor: Kgnneth J. U nwin. by WW /6i His Attorney.

K. J. UNWlN ELECTRIC SWITCH Jam 25, 1938.

Filed 061;. 31, 1936 2 Sheets-Sheet 2 Inventor:

MW H imtorn e3 m w n U J .n .L e n n e K Patented Jan. 25, 1938 PATENT OFFICE ELECTRIC SWITCH Kenneth J. Unwin, Schenectady, N. Y., asaignor to General Electric Company, a corporation of New York Application October 31, 1936, Serial No. 108,604

8 Claims.

My invention relates to electric switches, more particularly to reciprocally operable multiple contact switches, and has for an object the provision of a' compact switch of this character which is simple, reliable, and inexpensive.

In the control of automatic machinery, such for example as machine tools, it is often desirable to operate an electric switch at a predetermined point in the movement of the machine element so as to carry out the desired control function. Various types of limit switches operable in this manner have heretofore been proposed, many of which are highly satisfactory. In some cases, however, the space available immediately adjacent the moving machine element may be so limited as to preclude positioning an ordinary limit switch directly in the path of movement and accordingly resort has often been had to special lever systems for operating the limit switch..

Something is yet to be desired, therefore, in a limit switch of extremely small size and compact construction.

Furthermore, the various control sequences necessary to the control of different machines require different combinations of normally open, normally closed, overlapping or nonoverlapping' contacts and it will be'understood that it is not economically feasible to manufacture a wide variety of switches in order to provide these various combinations. While switches embodying my invention are not confined in their application to operation aslimit switches, and are capable of universal application, it is a further object of my invention to provide an extremely small multiple contact limit switch which is readily convertible either at the factory or in the field 'to provide any desired combination of normally open or normally closed contacts.

In carrying out my invention, I provide an electric switch comprising an insulating base having a longitudinal channel in one face, in which channel is disposed an operating bar guid- -ed by the walls of the channel for reciprocal movement and carrying movable switch members. Disposed on the base on the opposite sides of the channel I provide a plurality of fixed switch members, which are engageable with the movable switch members and which include portions extending inwardly from the sides of the channel to assist in guiding the operating bar.

More specifically, the base is formed of molded insulation material and is provided with a plurality of shoulders spaced along the sides of the channel, while each of the stationary switch members comprises a plate which rests on a face of one of the shoulders and is provided with an aperture for receiving the projecting tubular end of a metallic insert molded integrally with the shoulders. Secured to one edge of the plate and extending substantially at right angles thereto I provide a contact portion which engages a side of the shoulder to prevent rotation of the plate. which plate may be selectively positioned with the contact portion engaging either of two opposite sides of the shoulder.

The operating bar is provided with a plurality of longitudinally spaced grooves in its opposite sides and with a plurality of wiping springs and movable switch members slidable thereon. A plurality of U-shaped keys arranged to straddle the operating bar with the legs thereof disposed in selected ones of the spaced grooves are provided for positioning the movable switch members and the wiping springs on the operating bar so as selectively to provide normally open or normally closed contacts in accordance with the selected positions of the stationary switch member.

For a more complete understanding of my invention, reference should now be had to the drawings in which Fig. 1 is an elevational view of an electric switch embodying my invention having two pairs of normally open contacts; Fig. 2 is a similar view of the electric switch shown in Fig. 1 with the switch members reorganized so as to provide two pairs of normally closed contacts; Figs. 8 and 4 are similar views of the electric switch in which the switch members are arranged to provide one pair of normally open contacts and one pair of normally closed contacts, the switch shown in Fig. 4 being arranged to overlapping operation, i. e. the normally open contacts close before the normally closed contacts open; Fig. 5 is a view in exploded perspective of the electric switch shown in Fig. 1; Fig. 6 is a side view, partly in section, along line 6-6 of Fig. 2; Fig. 7 is a detail view of the reciprocally movable operating bar; and Fig. 8 is a sectional view taken along the line 8-8 of Fig. 2.

Referring now to Figs. 1 and 5 of the drawings, I have shown my invention as embodied in an electric switch comprising a base ill formed of molded insulation material and having a channel in one face thereof defined by back and side walls ii and i2 respectively. Arranged along the opposite sides of the channel and formed integrally with the base III are a plurality of shoulders l3, l4, and I5 which extend inwardly from the sides of the channel to provide restricted portions and thereby guide a reciprocal operating bar It for reciprocal movement along the channel, each of the shoulders extending outwardly from the face of the base It, as shown. Each of the outwardly extending portions of the shoulders l4 and i5 is provided with a sloping face l1, l3, l3, and 20, as shown best in Fig. 5. Extending from each of the sloping faces is the tubular end of a metallic insert 2| which is molded integrally with the associated shoulder, the insert being knurled as shown in Fig. 8 so as to prevent rotation thereof in the base. These tubular inserts serve to support the stationary switch members of the electric switch on the respective shoulders and since the switch members are identical, only the switch member associated with the sloping face l8 will be described in detail.

As shown best in Fig. 5, the stationary switch member comprises a terminal plate 22 having an aperture 23 therein for receiving the projecting end of the tubular insert 2|. The diameter of .this aperture 23 is such that a press fit is provided between the tubular insert 2i and the plate 22 so as securely to position the plate 22 on the sloping surface l8, while permitting the plate 22 to be readily pried loose for a purpose to be more fully described hereinafter. As shown, the tubular insert 2i is internally threaded and a suitable terminal screw 24 extends through the aperture 23 into threaded engagement with the insert 2|. Secured to one edge of the terminal plate 22 and extending substantially at right angles thereto so as to rest against a side face of the shoulder I4 is a contact portion 25 and the opposite ends of the plate 23 are provided with projecting portions 25, the purpose of which will be more fully described hereinafter.

As shown best in Figs. 5 and 7, the operating bar i6 is substantially rectangular in form and the opposite sides of the bar are provided with longitudinally spaced, transversely extending grooves 21, 28, 23, 3D, and 3|. Likewise, the operating bar i6 is provided intermediate its ends with enlarged portions 32 and 320. When the operating bar is disposed within the channel in the base ID, as shown in Fig. 1, these enlarged portions 32 and 32a lie within the restricted portion of the channel formed by the shoulder l4 and the extending ends 25 of the terminal plates 22 associated with the sloping surfaces H and I8 on the shoulder i4 extend inwardly over the channel and over the enlarged portions 32 and 32a of the operating bar l6 so as slidably to retain the operating bar in the channel. As shown the bar is also guided adjacent its opposite ends by the restricted portions formed by the shoulders i 3 and i5.

As shown best in Figs. 1 and 5, the operating bar is is provided on one side of the enlarged portion 32 with a spacing washer 33 which is slidable along the bar it, with a movable switch member 34, a wiping spring 35, and a substantially U-shaped key 38 which straddles the bar with the legs of the U disposed in the transverse grooves 28 so as resiliently to support the switch member 34 in engagement with the spacing washer 33.

Likewise, the operating bar It is provided with an insulating shield 31 adjacent the enlarged portion 32a, which shield is provided with portions extending laterally over the side walls i2 and with a portion extending inwardly to the back wall H of the channel in the base l0. Arranged on the opposite side of the shield 31 from the enlarged portion 32a is a wiping spring 38 and a movable switch member 33, the wiping spring 33 maintaining the switch member 33 in resilient engagement with a second U-shaped key 43, the legs of which are disposed in the transverse grooves 23.

In addition, the operating bar It carries at its lower end a third U-shaped key 4i and a spacing washer 42 similar to the washer 33. The key 4| and the spacing washer 42 are not necessary for the operation of the switch shown in Fig. 1, but are mounted on the bar It for convenience, the parts being utilized in reorganizing the switch so as to provide the modifications shown in Figs. 2, 3, and 4. In addition, these members 4| and 42 assist in guiding the operating bar It for longitudinal movement, one edge of these members engaging the rear wall ll of the channel in the base III, as shown best in Fig. 6. Likewise, the spacing washers 33 and 43, the insulating shield 31, and the spacing washer 33 engage the back wall ll so as to assist in guiding the operating bar It.

Each of the switch members 34 and 33 is provided with outwardly extending contact portions, 43 and 44 respectively, arranged to extend outwardly between the shoulders l3, I4, and I5 for engagement with the contact portions 25 of the stationary switch members. The operating bar it is normally biased to the position shown in Figs. 1 to 4 inclusive by a spring 46 which surrounds the bar [6, one end of the spring engaging the inwardly projecting portions of the shoulder l3 and the other end of the spring engaging a U-shaped key 41, the legs of which are disposed in the transverse groove 21. An operating knob 48, which is slidable transversely over the key 41 is provided on the uppermost end of the operating bar It, the knob 48 and the key 41 being normally held in position by the spring 46.

Normally the operating bar It is held in the biased position, shown in Fig. 1, by engagement of the extending ends of the switch member 34 with the shoulders 13 so as to provide a plurality of pairs of normally open contacts and it will be apparent that when the operating knob 48 is depressed, the operating bar It moves downwardly so as to engage the contact portions 43 and 44 of the movable switch members 34 and 33 with the associated contact portions 25 of the stationary switch members, the wiping springs 35 and 38 being compressed, aswill be more fully described hereinafter, and the key 40 engaging the inwardly extending portions of the shoulder l5 to limit the downward movement of the operating bar I6.

Referring now to Fig. 2, in order to change over from the normally open switch shown in Fig. l to the normally closed switch shown in Fig. 2, it is necessary only to reverse the stationary and movable switch members and the wiping springs and selectively to position the keys 35 and 40 in the positions shown in Fig. 2. To accomplish this, it is necessary first to remove the terminal screws 24 associated with the shoulder 14 and to remove the associated stationary switch members by D ying the plates 22 off of the inserts 2|. The operating bar l6 may be now removed from the channel, the lower end of the biasing spring 46 coming to rest against the key 36, as shown in Fig. 5. The upper end of the biasing spring 46 may then be forced downwardly and the knob 43 and the key 41 removed from the bar It, whereupon the biasing spring 43 may be slid over the end of the bar.

It will be apparent that the key 36 may now be removed from the grooves 23 so as to permit removal or thewiping spring 35, the switch member 34, and the spacer 33 by sliding them over the end oi the bar. In a similar manner, the keys 4| and 40 may be removed from the bar I! and the spacer 42, the switch member 33, the wiping spring 33, and the insulating shield 31 thereupon removed by sliding them over the lower end of the bar.

To reassemble the switch so as to provide a plurality of pairs of normally closed contacts. as shown in Fig. 2, the switch member 34 is reversed, as shown, and slid over the lower end oi. the bar IS, the wiping spring 35, and the insulating shield 31 then being slid upwardly over the lower end of the bar and the key 34 inserted in the grooves 23, as shown in Fig. 2. The key 43, which formerly occupied the grooves 29, is now inserted in the grooves 30, and the spacer 42, the switch member 39, in reversed position, and the wiping spring 33 are slid over the lower end of the bar l5 and the key 4i is then inserted in the groove 3|.

The operating bar l3 may now be replaced in the channel in the base ill and the stationary switch members may be replaced on the shoulders I 4 and i5 by pressing the terminal plates 22 over the inserts 2| with the contact portions 23 in the reversed position shown in Fig. 2. Completion oi the assembly is now accomplished by replacing the biasing spring 46, the key 41, and the operating knob 48 on the upper end of the operating bar l6, as shown, the key 40 in this arrangement engaging the inwardly extending portions of the shoulder l5 to limit the movement of the operating bar IS in accordance with its bias and the 'key 35 being arranged to engage the other side of the shoulder ii to limit the movement of the operating bar l6 when the knob 43 is depressed to open the switch contacts. Thus, it will be seen that my improved switch may be readily converted from a normally open to a normally closed switch simply by removing certain of the parts and reassembling them in selected positions.

Similarly, the normally open switch shown in Fig. i may be converted to a. switch having one pair of normally open contacts and a pair of normally closed contacts, as shown in Fig. 3. This may be accomplished by removing the stationary switch members associated with the shoulder l4, whereupon the operating bar I! may be removed from the channel, the keys 43 and M, the wiping spring 38. the switch member 33, and the spacer 42 removed from the operating bar i 6 and reassembled in the respective positions shown in Fig. 3. The stationary switch members,"

associated with the shoulder l5 may then be removed and replaced in the reverse pos tion shown, the operating bar l6 replaced in the channel, and the movable switch members associated with the shoulder I4 replaced in their original posi tion. as shown. I

When the switch is reassembled, as shown in Fig. 8, it will be observed that the contact portions 44 normally engage the stationary contact portions 25 associated with the shoulders N to provide a pair of normally closed contacts, while the movable contact portions 43 are spaced from the stationary contact portions 25 associated with the shoulder l4 to provide a pair of normally open contacts. When the control knob 43 is depressed, the normally closed contacts open and the normally open contacts close, the relation oi the parts being such that the normally closed contacts open prior to closure of the other contacts; that is, the contacts are in non-overlapping relation.

In some cases, it may be desirable to have the normally open contacts close before the normally closed contacts open. This may be accomplished simply by disassembling the switch, as described above, and by reassembling it, as shown in Fig. 4, the only change from Fig. 3 being that the spacer 33 between the switch member 34 and the en larged portion 32 of the bar it has been removed. For convenience, and in order to prevent the spacer 33 from being mislaid, it may be assembled, if desired, on the bar "adjacent the shield 31, as shown in Fig. 4.

In switches of this character, it is ordinarily desirable to provide a wiping or rolling action between the contacts so as to increase the life of the contacts and the current carrying capacity 01' the switch. This is accomplished very simply in my improved switch by arranging each of the movable switch members 34 and 39 so that the aperture therein through which the operating bar I3 extends is'ofiset from the imaginary line drawn between the centers of the contact portions 43 or 44. This arrangement is illustrated best in Figs. 5 and 6. Normally, the wiping springs 33 and 36 maintain the switch members 34 and 39 at right angles to the bar l6, as shown in Fig. 5, but it will be apparent that as soon as the movable contact portions 43 and 44 engage the associated stationary contact portions 25, the wiping springs tilt or twist the switching members 34 and 39 so as to provide a rolling motion of the movable contacts, the ilnal closed position being shown best in Figs. 2 and 6.

While. as stated above, my improved switch is particularly useful as a limit switch, it will be apparent that its application is not limited thereto and that it may find considerable use simply as a manually operable push-button switch, or it may be operated by any suitable electromagnetic or mechanical means. In some cases, it may be desirable to provide a larger number of contacts and accordingly the opposite ends of the base' 10 are respectively provided with a groove and a tongue so that a plurality of these switches may be arranged in end to end relation with the adjacent ends of the operating bar .IS in abutting relation, the control knobs 48 of course being removed from all except the end one of the switches. Thus, operation of the control knob associated with the end switch will effect operation of all of the bars l6 and the associated contacts.

In order to facilitate mounting of the switch on a suitable support, the shoulders l3 are provided with suitable apertures 49 in which suitable mounting studs may be inserted.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made and I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric switch comprising an insulating base having a longitudinal channel in one face thereof, spaced apart shoulders extending from said base on opposite sides of said channel, an operating member disposed in said channel and guided by the ,walls thereof for reciprocal movement, movable switch members carried by said operating member having contact portions extending outwardly from said channel between said spaced apart shoulders, and fixed switch members mounted on said shoulders having contact portions between said shoulders engageable with the contact portions of said movable switch members and having guide portions extending inwardly from said shoulders for slidably retaining said operating member in said channeL 2. An electric switch comprising an insulating base having a longitudinal channel in one face thereof, spaced apart shoulders extending outwardly from said base on opposite sides of said channel and extending inwardly from the walls of said channel to form restricted portions, an operating member disposed in said channel and guided by said shoulders for reciprocal movement,a movable switch member carried by said operating member having contact portions extending outwardly from said channel between said spaced apart shoulders, and fixed switch members mounted on said shoulders having contact portions engageable with the extending contact portions of said movable switch member and having guide portions extending inwardly over one of said restricted portions of said channel for slidably retaining said operating member therein.

3. An electric switch comprising an insulating base having a longitudinally extending channel in one face thereof, an operating bardisposed in said channel and guided by the walls thereof for reciprocal movement, said bar having a plurality of longitudinally spaced transverse grooves in the opposite sides thereof, a plurality of U-shaped keys disposed along and straddling said bar with the legs of said keys disposed in selected ones of said grooves, certain of said keys during movement of said bar slidably engaging the back-wall of said channel to assist in guiding said bar, a movable switch member, means including one of said keys for resiliently supporting said switch member on said bar, and fixed switch members supported on said base on opposite sides of said channel for engagement with said movable switch member, said fixed switch members having portions extending inwardly from the sides of said channel for slidably retaining said operating bar therein.

4. An electric switch comprising an insulating base having a longitudinal channel in one face thereof, spaced apart shoulders extending outwardly from said base on opposite sides of said channel and extending inwardly from the walls of said channel to form restricted portions, an operating bar disposed in said channel and guided by said shoulders for reciprocal movement, said bar having a plurality of longitudinally spaced grooves in the opposite sides thereof, a plurality of U-shaped keys disposed along and straddling said bar with the legs of said keys disposed in selected ones of said grooves, certain of said keys during movement of said bar slidably engaging the back wall of said channel between said shoulders to assist in guiding said bar, a movable switch member, means including one of said keys for resiliently supporting said switch member on said bar, said switch member having contact portions extending outwardly from said channel between said shoulders, and fixed switch members mounted on said shoulders having contact portions engageable with the extending contact portions of said movable switch member and having guide portions extending inwardly over one of said restricted portions for slidably retaining said operating bar in said channels.

5. An electric switch comprising a base formed arousal ofmouldedinmlaflngmatc'ialhavingapairof transversely spaced shoulders extending from one face thereof, metallic'inserts moulded intemil! with said base having tubular end portions extending from said shoulders, stationary switch members on said shoulders, each of said switch members including a plate having an aperture for receiving the extending end of one of said inserts and a contact portion extending substantially at right angles to said plate for engaging a side of the associated shoulder thereby to prevent rotation of said plate on said insert, an operating member disposed between-said shoulders for slidable movement along said base, movable switch means carrled by said operating member for engagement with the contact portions of said stationary contacts, and means including portions of said plates extending inwardly from said shoulders for guiding said operating member.

6. An electric switch comprising a base formed of moulded insulating material having a longitudinal channel in one face thereof and spaced apart shoulders extending outwardly from said base on opposite sides of said channel, metallic inserts moulded integrally with said base having tubular end portions extending outwardly from said shoulders, stationary switch members mounted on said shoulders each of said switch members including a plate having an aperture for receiving the extending end of one of said inserts and a contact portion secured to an edge of said plate for engaging a side of the associated shoulder to prevent rotation of said plate on said insert, an operating member disposed in said channel and guided by the walls thereof for reciprocal movement, movable switch members carried by said operating member having contact portions engageable with the contact portions of said stationary switch members, and means including portions of said stationary switch members extending inwardly from said shoulders for slidably retaining said operating member in said channel.

7. An electric switch comprising an insulating base having a longitudinal channel in one face thereof, an operating bar disposed in said channel and guided by the-walls thereof for reciprocal movement, said operating bar having a plurality of transverse grooves in the opposite sides thereof, a plurality of stationary switch member's, detachable means for selectively securing said switch members to said base on the opposite sides of said channel in either of two positions, a plurality of movable switch members each of which is provided with an aperture through which said operating bar extends, wiping springs surrounding said bar associated with said movable switch member, and a plurality of substantially U- shaped keys selectively engageable in said transverse grooves for positioning said movable switch member and said wiping springs on said bar selectively to provide normally open or normally closed switches in accordance with the selected positions of said stationary switch members, and means including portions extending from said stationary switch member for slidably retaining said operating bar in said channel.

8. An electric switch comprising an insulating base having a longitudinal channel in one face thereof, an operating bar disposed in said chantachable means for selectively securing said switch members to said base on the opposite sides of said channel in either of two selected positions, a plurality of movable switch members each of which is provided with an aperture through which said operating bar extends, wiping springs surrounding said bar associated with said movable switch members, said wiping springs and said movable switch members being slidable over the ends of said bar, a plurality of substantially U-shaped keys transversely slidable into selected ones of said grooves on said bar, means for biasing said operating bar to a predetermined position, means including said keys for positioning said movable switch members and said wiping springs on said bar selectively to provide either normally open or normally closed switches in acv cordance with the selected positions of said stationary switch members, means including portions extending from said stationary switch members when in either of said two positions for slidably retaining said operating bar in said channel, and means including at least one of said keys for limiting the reciprocal movement of said bar.

KENNETH" J. UNWIN. 

